Voltage-controlled oscillator and phase-locked loop

Abstract

The invention relates to a voltage-controlled oscillator and a phase-locked loop. The voltage-controlled oscillator comprises an input circuit, a first current supply circuit, a second current supply circuit, a filter circuit and an oscillation circuit. The input circuit comprises an operational amplifier and a first input transistor. The operational amplifier is used for generating an output voltage according to an input voltage and a feedback voltage. The first input transistor is used for generating an input current according to an output voltage and a power supply voltage. The first current supply circuit is used for generating a first output current according to an input current. The second current supply circuit is used for generating a second output current according to the input current. The filter circuit is coupled to the input circuit and the second current supply circuit and is used for reducing the influence of the change of the input current on the second current supply circuit. The oscillating circuit is used for generating an output clock according to the first output current and the second output current.

Description

Technical Field

[0001] The present application relates to an oscillator and a phase-locked loop, and in particular to a voltage-controlled oscillator and a phase-locked loop using the voltage-controlled oscillator. Background Art

[0002] High-gain voltage-controlled oscillators are more tolerant to the effects of process, temperature, and voltage. However, with the more stringent jitter requirements of product specifications, high-gain voltage-controlled oscillators must use a large loop filter to meet the jitter requirements. The loop filter must even be implemented via external capacitors on the chip, which increases the circuit area and cost.

[0003] In addition, in a voltage-controlled oscillator, a transistor can be used to convert the input voltage into a current to control the oscillation frequency of the oscillator. However, based on the characteristics of the transistor, the input voltage must be at least greater than the threshold voltage (Vth) of the transistor, which limits the input voltage and further affects the voltage operating range of the phase-locked loop using the voltage-controlled oscillator. In addition, if the current source of the voltage-controlled oscillator is implemented with a transistor, it is more sensitive to the jitter of the power supply. Therefore, the voltage-controlled oscillator has higher requirements for the power supply and requires a power supply with less noise.

[0004] Furthermore, when the phase-locked loop using a voltage-controlled oscillator is started, the internal capacitors and resistors greatly affect the stability of the phase-locked loop. Therefore, an additional compensation circuit is usually configured for compensation. However, the above compensation circuit will cause additional power consumption, and in steady state, the compensation circuit is of little help to the voltage-controlled oscillator. In addition, the transistors in the compensation circuit will produce poles during operation, which seriously affects the stability of the phase-locked loop. In addition, different frequencies have an impact on the corner frequency of the voltage-controlled (VC) circuit. In addition to considering the transistors of the voltage-controlled oscillator, the resistors must also be considered, which increases the difficulty of circuit design. Summary of the invention

[0005] In view of the deficiencies of the prior art, one of the purposes of the present invention is (but not limited to) to provide a voltage-controlled oscillator and a phase-locked loop to improve the deficiencies of the prior art.

[0006] In some embodiments, the voltage-controlled oscillator includes an input circuit, a first current supply circuit, a second current supply circuit, a filter circuit, and an oscillation circuit. The input circuit includes an operational amplifier and a first input transistor. The operational amplifier is used to generate an output voltage according to an input voltage and a feedback voltage. The first input transistor is used to generate an input current according to the output voltage and a power supply voltage. The first current supply circuit is used to generate a first output current according to the input current. The second current supply circuit is used to generate a second output current according to the input current. The filter circuit couples the input circuit and the second current supply circuit and is used to reduce the influence of the change of the input current on the second current supply circuit. The oscillation circuit is used to generate an output clock according to the first output current and the second output current.

[0007] In some embodiments, the phase-locked loop includes a phase frequency detector, a charge pump, a first filtering circuit, a voltage-controlled oscillator, and a loop frequency divider. The phase frequency detector is used to detect the difference between the reference clock and the feedback clock, thereby outputting a detection signal. The charge pump is used to generate a charge / discharge signal according to the detection signal. The first filtering circuit is used to determine the input voltage according to the charge / discharge signal. The voltage-controlled oscillator includes an input circuit, a first current supply circuit, a second current supply circuit, a second filtering circuit, and an oscillation circuit. The input circuit includes an operational amplifier and a first input transistor. The operational amplifier is used to generate an output voltage according to the input voltage and the feedback voltage. The first input transistor is used to generate an input current according to the output voltage and the power supply voltage. The first current supply circuit is used to generate a first output current according to the input current. The second current supply circuit is used to generate a second output current according to the input current. The second filtering circuit couples the input circuit and the second current supply circuit, and is used to reduce the influence of the change of the input current on the second current supply circuit. The oscillation circuit is used to generate an output clock according to the first output current and the second output current. The loop frequency divider is used to generate a feedback clock according to the output clock. The ratio of the filtering bandwidth of the second filtering circuit to the loop bandwidth of the phase-locked loop is not greater than 1%.

[0008] The technical means embodied in the embodiments of the present application can improve at least one of the shortcomings of the prior art. The voltage-controlled oscillator of the present application uses an operational amplifier to receive the input voltage, and through the negative feedback mechanism of the operational amplifier, a lower input voltage can adjust the transistor to generate current to control the oscillation frequency of the oscillator. Therefore, the voltage-controlled oscillator of the present application has a wider input voltage range, so the phase-locked loop using the voltage-controlled oscillator also has a wider voltage operating range.

[0009] In addition, the voltage-controlled oscillator and phase-locked loop of the present application use the negative feedback mechanism of the operational amplifier to adjust the transistor, so the voltage-controlled oscillator and phase-locked loop of the present application have a better power supply rejection ratio (PSRR), and therefore have lower requirements for power supply. Furthermore, the voltage-controlled oscillator and phase-locked loop of the present application only need to consider the influence of the transistor on the corner frequency in circuit design, and do not need to consider the influence of the resistor, so that the difficulty of circuit design can be reduced.

[0010] The features, implementation and effects of the present application are described in detail below with reference to the drawings as preferred embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic diagram of a voltage-controlled oscillator is drawn according to some embodiments of the present application;

[0012] Figure 2 A schematic diagram of a voltage-controlled oscillator is drawn according to some embodiments of the present application;

[0013] Figure 3 A schematic diagram of a voltage-controlled oscillator according to some embodiments of the present application; and

[0014] Figure 4 A schematic diagram of a phase-locked loop is drawn according to some embodiments of the present application. DETAILED DESCRIPTION

[0015] All words used herein have their ordinary meanings. The definitions of the above words in commonly used dictionaries and the use examples of any words discussed herein in the content of this application are only examples and should not limit the scope and meaning of this application. Similarly, this application is not limited to the various embodiments shown in this specification.

[0016] As used herein, "coupled" or "connected" may refer to two or more elements making direct physical or electrical contact with each other, or making indirect physical or electrical contact with each other, or may refer to two or more elements operating or acting on each other. As used herein, the term "circuit" may refer to a device composed of at least one transistor and / or at least one active and passive element connected in a certain manner to process signals.

[0017] As used herein, the term "and / or" includes any combination of one or more of the listed associated items. In this article, the words first, second, and third are used to describe and distinguish each element. Therefore, the first element in this article can also be called the second element without departing from the original intention of this application. For ease of understanding, similar elements in each figure will be designated with the same reference numeral.

[0018] In order to improve the problem in the prior art that the input voltage of the voltage-controlled oscillator is limited, thereby affecting the voltage operating range of the phase-locked loop using the voltage-controlled oscillator, to improve the problem in the prior art that the voltage-controlled oscillator has high requirements for power supply, and to improve the problem in the prior art that the circuit design is difficult, the present application proposes a voltage-controlled oscillator and a phase-locked loop, which are described in detail as follows.

[0019] Figure 1 A schematic diagram of a voltage-controlled oscillator 100 is drawn according to some embodiments of the present application. As shown in the figure, the voltage-controlled oscillator 100 includes an input circuit 110, a first current supply circuit 120, a second current supply circuit 130, a filter circuit 140, and an oscillation circuit 150. The input circuit 110 includes an operational amplifier OP and a first input transistor MI1. The operational amplifier OP is coupled to the first input transistor MI1, the first current supply circuit 120, and the filter circuit 140, and is coupled to the second current supply circuit 130 through the filter circuit 140. The first current supply circuit 120 and the second current supply circuit 130 are coupled to the oscillation circuit 150.

[0020] In one embodiment, the operational amplifier OP is used to generate an output voltage Vop according to an input voltage Vin and a feedback voltage Vfb. Subsequently, the first input transistor MI1 is used to generate an input current Iin according to the output voltage Vop and the power supply voltage VDD. The first current supply circuit 120 is used to generate a first output current Io1 according to the input current Iin. The second current supply circuit 130 is used to generate a second output current Io2 according to the input current Iin. The filter circuit 140 couples the input circuit 110 and the second current supply circuit 130, and is used to reduce the influence of the change of the input current Iin on the second current supply circuit 130. In some embodiments, the filter circuit 140 includes a passive low-pass filter, which includes a capacitor C1 and a resistor R1. The present application can configure the filter circuit 140 between the input circuit 110 and the second current supply circuit 130, so as to reduce the influence of the change of the input current Iin on the second current supply circuit 130 with strong current driving capability. The oscillation circuit 150 is used to generate an output clock according to the first output current Io1 and the second output current Io2.

[0021] It should be noted that, if viewed from the input voltage Vin, the voltage-controlled oscillator 100 of the present application is similar to a linear regulator (Low Dropout Regulator, LDO) architecture. Through the negative feedback mechanism of the operational amplifier OP, a lower input voltage Vin can adjust the gate-source voltage (Vgs) of the first input transistor MI1 and thereby generate a current to control the oscillation frequency of the oscillation circuit 150. Therefore, the voltage-controlled oscillator 100 of the present application has a wider input voltage Vin range, so that the phase-locked loop using the voltage-controlled oscillator 100 of the present application also has a wider voltage operating range.

[0022] In some embodiments, the second output current Io2 generated by the second current supply circuit 130 is greater than the first output current Io1 generated by the first current supply circuit 120. It can be seen that the current driving capability of the second current supply circuit 130 is stronger than the current driving capability of the first current supply circuit 120. For example, the current ratio of the second output current Io2 to the first output current Io1 can be a value between 10 and 40. The filter circuit 140 is coupled between the input circuit 110 and the second current supply circuit 130 to reduce the influence of the change of the input current Iin on the second current supply circuit 130 with strong current driving capability, thereby reducing the influence of the change of the input voltage Vin (caused by factors such as process, temperature, voltage, etc.) on the oscillation circuit 150. At the same time, the filter circuit 140 does not affect the first current supply circuit 120 with weak current driving capability. Therefore, the change of the input voltage Vin will be immediately reflected on the output of the oscillation circuit 150 through the change of the first output current Io1, but the smaller first output current Io1 will not cause excessive influence.

[0023] In some embodiments, the first input transistor MI1 includes a high voltage terminal, a control terminal and a low voltage terminal. The high voltage terminal of the first input transistor MI1 is used to receive the power supply voltage VDD. The control terminal of the first input transistor MI1 is used to receive the output voltage Vop. The low voltage terminal of the first input transistor MI1 is used to output the input current Iin.

[0024] In some embodiments, the operational amplifier OP includes an inverting terminal, a non-inverting terminal, and an output terminal. The inverting terminal of the operational amplifier OP is used to receive the input voltage Vin. The non-inverting terminal of the operational amplifier OP is coupled to the low voltage terminal (such as the lower terminal) of the first input transistor MI1, and is used to receive the feedback voltage Vfb. The output terminal of the operational amplifier OP is coupled to the control terminal of the first input transistor MI1, and is used to output the output voltage Vop. In some embodiments, the output terminal of the operational amplifier OP is coupled to the second current supply circuit 130 through the filter circuit 140.

[0025] In some embodiments, the input circuit 110 further includes a second input transistor MI2. The second input transistor MI2 includes a high voltage terminal, a control terminal, and a low voltage terminal. The high voltage terminal (such as the upper terminal) of the second input transistor MI2 is coupled to the low voltage terminal (such as the lower terminal) of the first input transistor MI1 and the non-inverting terminal of the operational amplifier OP. The control terminal of the second input transistor MI2 is coupled to its own high voltage terminal (such as the upper terminal) to form an equivalent diode. The low voltage terminal of the second input transistor MI2 is coupled to the low potential terminal (such as the ground terminal). As shown in the figure, the input circuit 110 of the voltage-controlled oscillator 100 is only configured with a transistor but not a resistor. Therefore, in circuit design, only the influence of the transistor on the corner frequency needs to be considered, and the influence of the resistor does not need to be considered. In this way, the difficulty of circuit design can be reduced.

[0026] In some embodiments, the second input transistor MI2 of the input circuit 110 may also be replaced by a resistor, or implemented by a transistor in a linear region, so as to improve the linearity of the gain (KVCO) of the voltage controlled oscillator 100 .

[0027] In some embodiments, the first current supply circuit 120 includes a first output transistor Mo1. The first output transistor Mo1 includes a high voltage terminal, a control terminal, and a low voltage terminal. The high voltage terminal of the first output transistor Mo1 is used to receive a power supply voltage VDD. The control terminal of the first output transistor Mo1 is coupled to the output terminal of the operational amplifier OP and is used to receive the output voltage Vop. The low voltage terminal of the first output transistor Mo1 is used to generate a first output current Io1.

[0028] In some embodiments, the second current supply circuit 130 includes a second output transistor Mo2. The second output transistor Mo2 includes a high voltage terminal, a control terminal, and a low voltage terminal. The high voltage terminal of the second output transistor Mo2 is used to receive the power supply voltage VDD. The control terminal of the second output transistor Mo2 is coupled to the output terminal of the operational amplifier OP through the filter circuit 140, and is used to receive the output voltage Vop. The low voltage terminal of the second output transistor Mo2 is used to generate the second output current Io2.

[0029] In some embodiments, the first input transistor MI1 and the first output transistor Mo1 form a current mirror. Based on the principle of the current mirror, the current ratio of the first output current Io1 flowing through the first output transistor Mo1 to the input current Iin flowing through the first input transistor MI1 is a specific value (e.g., a fixed value, or one of several predetermined ratios of the adjustable current mirror). The current ratio Io1 / Iin can be determined by determining the size ratio of the first output transistor Mo1 and the first input transistor MI1 or an equivalent relationship thereof (e.g., the ratio of the number of transistor units of the first output transistor Mo1 to the number of transistor units of the first input transistor MI1).

[0030] As mentioned above, the first input transistor MI1 and the second output transistor Mo2 also form a current mirror. Based on the principle of the current mirror, the current ratio of the second output current Io2 flowing through the second output transistor Mo2 to the input current Iin flowing through the first input transistor MI1 is a specific value (e.g., a fixed value, or one of several predetermined ratios of the adjustable current mirror). By determining the size ratio of the second output transistor Mo2 and the first input transistor MI1 or its equivalent relationship (e.g., the ratio of the number of transistor units of the second output transistor Mo2 to the number of transistor units of the first input transistor MI1), the current ratio Io2 / Iin can be determined. In this way, the voltage-controlled oscillator 100 of the present application uses the negative feedback mechanism of the operational amplifier OP so that a lower input voltage Vin can adjust the gate-source voltage (Vgs) of the first input transistor MI1, and at the same time adjust the current of the first output transistor Mo1 and the second output transistor Mo2 through the principle of the current mirror. It can be seen that the voltage-controlled oscillator 100 of the present application controls the first output transistor Mo1 and the second output transistor Mo2 through the negative feedback mechanism of the operational amplifier OP. In other words, the gate voltages of the first output transistor Mo1 and the second output transistor Mo2 are determined by the operational amplifier OP. Therefore, the voltage-controlled oscillator 100 of the present application has a better power supply rejection ratio (PSRR), and therefore has lower requirements for power supply.

[0031] In some embodiments, the first input transistor MI1, the first output transistor Mo1, and the second output transistor Mo2 may be P-type Metal-Oxide-Semiconductor Field-Effect Transistor (PMOSFET), and the second input transistor MI2 may be N-type Metal-Oxide-Semiconductor Field-Effect Transistor (NMOSFET). However, this application does not Figure 1 The above-mentioned embodiments are limited to the above-mentioned embodiments, and the types of the first input transistor MI1, the second input transistor MI2, the first output transistor Mo1 and the second output transistor Mo2 can be changed according to actual needs. In addition, the high voltage terminal and the low voltage terminal shown in the above-mentioned embodiments can be the source terminal and the drain terminal of the P-type metal oxide semiconductor field effect transistor, respectively, the high voltage terminal and the low voltage terminal can be the drain terminal and the source terminal of the N-type metal oxide semiconductor field effect transistor, respectively, and the control terminal can be the gate terminal of the two types of transistors.

[0032] In some embodiments, the filter circuit 140 includes a capacitor C1 and a resistor R1. The capacitor C1 is used to receive the power supply voltage VDD. The resistor R1 is coupled to the output terminal of the operational amplifier OP, the control terminal of the first input transistor MI1, the control terminal of the first output transistor Mo1, and the control terminal of the second output transistor Mo2.

[0033] In some embodiments, the resistor R1 includes a first end and a second end. The first end (such as the left end) of the resistor R1 is coupled to the output end of the operational amplifier OP, and the second end (such as the right end) of the resistor R1 is coupled to the capacitor C1 and the control end of the second output transistor Mo2.

[0034] In some embodiments, the filter circuit 140 may be a passive low-pass filter. In other embodiments, the filter circuit 140 may also be an active low-pass filter, which may be composed of a capacitor and an operational amplifier. When the voltage-controlled oscillator 100 is in a steady state, the high-frequency noise will be filtered out by the filter circuit 140. In other words, the effective gain (KVCO) of the voltage-controlled oscillator 100 is relatively small.

[0035] In some embodiments, the oscillation circuit 150 includes a ring oscillator including a plurality of oscillation units. Each oscillation unit (eg, inverter) is driven by a first output current Io1 and a second output current Io2 to generate a clock according to the output of the previous oscillation unit.

[0036] In some embodiments, the oscillator circuit 150 may be a single-ended oscillator. Figure 1 The embodiments shown are limited. For other embodiments, please refer to Figure 2 The oscillator circuit 250 of the present invention can also be implemented by a double-ended oscillator, depending on the actual needs. Figure 2 In addition to the oscillator circuit 250 and Figure 1 The oscillator circuit 150 is different from the oscillator circuit 150 of FIG. 1 , and the structures and operations of the remaining input circuit 210, the first current supply circuit 220, the second current supply circuit 230 and the filter circuit 240 are similar to those of FIG. 1 . Figure 1 The input circuit 110, the first current supply circuit 120, the second current supply circuit 130 and the filter circuit 140 are described in detail herein.

[0037] Figure 3 A schematic diagram of a voltage controlled oscillator 300 is drawn according to some embodiments of the present application. Figure 1 The first current supply circuit 120 and the second current supply circuit 130 of the voltage controlled oscillator 100 are implemented by using P-type metal oxide semiconductor field effect transistors. Figure 3 The first current supply circuit 320 and the second current supply circuit 330 of the voltage controlled oscillator 300 can be implemented by using N-type metal oxide semiconductor field effect transistors. In response to the above adjustment, Figure 3 The architecture and operation of the voltage controlled oscillator 300 are similar to Figure 1 The voltage controlled oscillator 100 is different and will be described in detail below.

[0038] In some embodiments, compared to Figure 1 The input circuit 110, Figure 3 The input circuit 310 further includes a third input transistor MI3. The third input transistor MI3 is used to generate a mirror current Imi according to the input current Iin. In some embodiments, the third input transistor MI3 includes a high voltage end, a control end, and a low voltage end. The high voltage end of the third input transistor MI3 is used to receive a power supply voltage VDD. The control end of the third input transistor MI3 is coupled to the output end of the operational amplifier OP and is used to receive the output voltage Vop. The low voltage end of the third input transistor MI3 is used to output the mirror current Imi.

[0039] In some embodiments, compared to Figure 1 The input circuit 110, Figure 3The input circuit 310 further includes a fourth input transistor MI4. The fourth input transistor MI4 includes a high voltage terminal, a control terminal and a low voltage terminal. The high voltage terminal of the fourth input transistor MI4 is coupled to the low voltage terminal (such as the lower terminal) of the third input transistor MI3. The control terminal of the fourth input transistor MI4 is coupled to its own high voltage terminal to form an equivalent diode. The low voltage terminal of the fourth input transistor MI4 is coupled to a low potential terminal (such as a ground terminal).

[0040] In some embodiments, the first current supply circuit 320 includes a first output transistor Mo1. The first output transistor Mo1 includes a high voltage terminal, a control terminal, and a low voltage terminal. The high voltage terminal of the first output transistor Mo1 is coupled to the oscillation circuit 350. The control terminal of the first output transistor Mo1 is coupled to the low voltage terminal (such as the lower terminal) of the third input transistor MI3 and the high voltage terminal (such as the upper terminal) of the fourth input transistor MI4. The low voltage terminal of the first output transistor Mo1 is coupled to a low potential terminal (such as a ground terminal). Compared to Figure 1 The first output transistor Mo1 of the first current supply circuit 120 is implemented by a P-type metal oxide semiconductor field effect transistor. Figure 3 The first output transistor Mo1 of the first current supply circuit 320 is implemented by an N-type metal oxide semiconductor field effect transistor.

[0041] In some embodiments, the second current supply circuit 330 includes a second output transistor Mo2. The second output transistor Mo2 includes a high voltage end, a control end, and a low voltage end. The high voltage end of the second output transistor Mo2 is coupled to the oscillation circuit 350. The control end of the second output transistor Mo2 is coupled to the low voltage end (such as the lower end) of the third input transistor MI3 and the high voltage end (such as the upper end) of the fourth input transistor MI4 through the filter circuit 340. The low voltage end of the second output transistor Mo2 is coupled to the low potential end (such as the ground end). Compared to Figure 1 The second output transistor Mo2 of the second current supply circuit 130 is implemented by a P-type metal oxide semiconductor field effect transistor. Figure 3 The second output transistor Mo2 of the second current supply circuit 330 is implemented by an N-type metal oxide semiconductor field effect transistor.

[0042] In some embodiments, compared to Figure 1 The filter circuit 140, Figure 3The capacitor C1 of the filter circuit 340 is coupled to a low potential end (such as a ground end). The resistor R1 of the filter circuit 340 is coupled to a low voltage end (such as a lower end) of the third input transistor MI3, a high voltage end (such as an upper end) of the fourth input transistor MI4, a control end of the fourth input transistor MI4 and a control end of the first output transistor Mo1, and is coupled to a control end of the second output transistor Mo2.

[0043] In some embodiments, compared to Figure 1 The filter circuit 140, Figure 3 The first end (such as the left end) of the resistor R1 of the filter circuit 340 is coupled to the low voltage end (such as the lower end) of the third input transistor MI3 and the high voltage end (such as the upper end) of the fourth input transistor MI4. The second end (such as the right end) of the resistor R1 of the filter circuit 340 is coupled to the capacitor C1 and the control end of the second output transistor Mo2. In some embodiments, compared to Figure 1 The oscillator circuit 150, Figure 3 One end of the oscillation circuit 350 is used to receive the power supply voltage VDD, and the other end of the oscillation circuit 350 is coupled to the high voltage end (such as the upper end) of the first output transistor Mo1 and the high voltage end (such as the upper end) of the second output transistor Mo2.

[0044] In addition to the aforementioned voltage controlled oscillators 100 , 200 , and 300 , the present application also includes a phase locked loop. Figure 4 A schematic diagram of a phase-locked loop 400 is drawn according to some embodiments of the present application. Figure 4 The phase-locked loop 400 includes a phase frequency detector (PFD) 410 , a charge pump (CP) 420 , a filter 430 , a voltage-controlled oscillator (VCO) 440 , and a loop divider (LD) 450 .

[0045] In one embodiment, the phase frequency detector 410 is used to detect the reference clock Clk. REF With feedback clock Clk FEEDBACK The difference between the two signals is used to output a detection signal. The charge pump 420 is used to generate a charge / discharge signal according to the detection signal. The filter circuit 430 is used to determine the input voltage according to the charge / discharge signal. The voltage-controlled oscillator 440 is used to generate an output clock according to the input signal. The loop frequency divider 450 is used to generate a feedback clock Clk according to the output clock. FEEDBACKThe phase frequency detector 410, the charge pump 420, the filter circuit 430 and the loop frequency divider 450 can be implemented by known or self-developed technologies, so their details are omitted here. The voltage controlled oscillator 440 can be Figures 1 to 3 The voltage controlled oscillator 100, 200, 300 or the equivalent thereof. It is worth noting that Figure 4 The embodiment can further enable the filter circuit (eg Figures 1 to 3 The ratio of the filtering bandwidth of the filters 140, 240, 340) to the loop bandwidth of the phase-locked loop 400 is not greater than 0.01 to achieve better performance.

[0046] Since those with ordinary knowledge in this field can refer to Figures 1 to 3 To understand the example of Figure 4 Details and variations of the embodiments of Figures 1 to 3 The technical features of the embodiments can be reasonably applied to Figure 4 In the embodiment of Figures 1 to 3 The relevant technical features of the embodiments are not described in detail here.

[0047] In summary, the voltage controlled oscillator and phase locked loop provided in some embodiments of the present application have a smaller effective gain (KVCO) and better phase noise. Therefore, the loop filter can use a smaller compensation capacitor to save area and cost.

[0048] In addition, the voltage-controlled oscillator uses an operational amplifier to receive input voltage, and through the negative feedback mechanism of the operational amplifier, a lower input voltage can adjust the transistor to generate current to control the oscillation frequency of the oscillator. Therefore, the voltage-controlled oscillator of the present application has a wider input voltage range, so the phase-locked loop using the voltage-controlled oscillator also has a wider voltage operating range.

[0049] In addition, the voltage-controlled oscillator and phase-locked loop of the present application use the negative feedback mechanism of the operational amplifier to adjust the transistor. Therefore, the voltage-controlled oscillator and phase-locked loop of the present application have a better power supply rejection ratio (PSRR), so the power supply requirement is lower. Furthermore, the voltage-controlled oscillator and phase-locked loop of the present application only need to consider the influence of the transistor on the corner frequency in circuit design, and do not need to consider the influence of the resistor, so that the difficulty of circuit design can be reduced.

[0050] Although the embodiments of the present application are described above, these embodiments are not intended to limit the present application. A person having ordinary knowledge in the technical field may make changes to the technical features of the present case according to the explicit or implicit contents of the present application. All these changes may fall within the scope of patent protection sought by the present application. In other words, the scope of patent protection of the present application shall be subject to the scope of the patent application defined in this specification.

[0051]

Explanation of symbols

[0052] 100, 200, 300: Voltage controlled oscillator

[0053] 110, 210, 310: Input circuit

[0054] 120, 220, 320: first current supply circuit

[0055] 130, 230, 330: second current supply circuit

[0056] 140, 240, 340: Filter circuit

[0057] 150, 250, 350: Oscillator circuit

[0058] 400: Phase-locked loop

[0059] 410: Phase frequency detector

[0060] 420: Charge Pump

[0061] 430: Filter circuit

[0062] 440: Voltage Controlled Oscillator

[0063] 450: Loop frequency divider

[0064] C1: Capacitor

[0065] Clk REF :Reference clock

[0066] Clk FEEDBACK :Feedback Clock

[0067] Iin: Input current

[0068] Imi: mirror current

[0069] Io1: first output current

[0070] Io2: Second output current

[0071] MI1: First input transistor

[0072] MI2: Second input transistor

[0073] MI3: Third input transistor

[0074] MI4: Fourth input transistor

[0075] Mo1: First output transistor

[0076] Mo2: Second output transistor

[0077] OP: Operational Amplifier

[0078] R1: Resistor

[0079] VDD: power supply voltage

[0080] Vfb: Feedback voltage

[0081] Vin: Input voltage

[0082] Vop: output voltage.

Claims

1. A voltage-controlled oscillator, comprising: An input circuit comprising: an operational amplifier for generating an output voltage according to an input voltage and a feedback voltage; and a first input transistor for generating an input current according to the output voltage and a power supply voltage; a first current supply circuit, configured to generate a first output current according to the input current; a second current supply circuit, configured to generate a second output current according to the input current; a filter circuit, coupling the input circuit and the second current supply circuit, and used to reduce the influence of the change of the input current on the second current supply circuit; as well as An oscillating circuit is used to generate an output clock according to the first output current and the second output current.

2. The voltage controlled oscillator according to claim 1, wherein: The second output current is greater than the first output current.

3. The voltage controlled oscillator according to claim 1, wherein: The first input transistor comprises: A high voltage terminal for receiving the power supply voltage; a control terminal for receiving the output voltage; and a low voltage terminal for outputting the input current; The operational amplifier includes: an inverting terminal for receiving the input voltage; a non-inverting terminal coupled to a low voltage terminal of the first input transistor and used for receiving the feedback voltage; and An output terminal is coupled to a control terminal of the first input transistor and is used to output the output voltage.

4. The voltage controlled oscillator according to claim 1, wherein: The input circuit also includes: A second input transistor, comprising: A high voltage terminal coupled to a low voltage terminal of the first input transistor and a non-inverting terminal of the operational amplifier; a control terminal coupled to the high voltage terminal of the second input transistor; and A low voltage terminal is coupled to a low potential terminal.

5. The voltage controlled oscillator according to claim 1, wherein: The first current supply circuit comprises: A first output transistor, comprising: A high voltage terminal for receiving the power supply voltage; a control terminal coupled to an output terminal of the operational amplifier and configured to receive the output voltage; and A low voltage terminal, used to generate the first output current; Wherein, the second current supply circuit comprises: A second output transistor, comprising: A high voltage terminal for receiving the power supply voltage; a control terminal coupled to the output terminal of the operational amplifier through the filter circuit and used for receiving the output voltage; and A low voltage terminal is used to generate the second output current.

6. The voltage controlled oscillator according to claim 5, wherein: The filter circuit includes: a capacitor for receiving the power supply voltage; and a resistor coupled to the output terminal of the operational amplifier and the control terminal of the second output transistor, wherein the resistor comprises: a first terminal coupled to the output terminal of the operational amplifier; and A second terminal is coupled to the capacitor and the control terminal of the second output transistor.

7. The voltage controlled oscillator according to claim 4, wherein: The input circuit also includes: A third input transistor, used to generate a mirror current according to the input current, wherein the third input transistor comprises: A high voltage terminal for receiving the power supply voltage; a control terminal coupled to an output terminal of the operational amplifier and configured to receive the output voltage; and A low voltage terminal for outputting the mirror current; A fourth input transistor, comprising: a high voltage terminal coupled to the low voltage terminal of the third input transistor; a control terminal coupled to the high voltage terminal of the fourth input transistor; and A low voltage terminal is coupled to the low potential terminal.

8. The voltage controlled oscillator according to claim 7, wherein: The first current supply circuit comprises: A first output transistor, comprising: A high voltage terminal coupled to the oscillation circuit; a control terminal coupled to the low voltage terminal of the third input transistor and the high voltage terminal of the fourth input transistor; and A low voltage terminal coupled to the low potential terminal; Wherein, the second current supply circuit comprises: A second output transistor, comprising: A high voltage terminal coupled to the oscillating circuit; a control terminal coupled to the low voltage terminal of the third input transistor and the high voltage terminal of the fourth input transistor through the filter circuit; and A low voltage terminal is coupled to the low potential terminal.

9. The voltage controlled oscillator according to claim 8, wherein: The filter circuit includes: a capacitor coupled to the low potential end; and a resistor coupled to the low voltage terminal of the third input transistor and the high voltage terminal of the fourth input transistor, and coupled to the control terminal of the second output transistor, wherein the resistor comprises: a first terminal coupled to the low voltage terminal of the third input transistor and the high voltage terminal of the fourth input transistor; and A second terminal is coupled to the capacitor and the control terminal of the second output transistor.

10. A phase-locked loop comprising: a phase frequency detector for detecting a difference between a reference clock and a feedback clock to output a detection signal; a charge pump, for generating a charge / discharge signal according to the detection signal; a first filtering circuit, for determining an input voltage according to the charge / discharge signal; A voltage controlled oscillator, comprising: An input circuit comprising: an operational amplifier, configured to generate an output voltage according to the input voltage and a feedback voltage; and a first input transistor for generating an input current according to the output voltage and a power supply voltage; a first current supply circuit, configured to generate a first output current according to the input current; a second current supply circuit, configured to generate a second output current according to the input current; A second filter circuit is coupled to the input circuit and the second current supply circuit, and is used to reduce the influence of the change of the input current on the second current supply circuit; as well as an oscillating circuit for generating an output clock according to the first output current and the second output current; and A first-loop frequency divider is used to generate the feedback clock according to the output clock, Wherein, a ratio of a filtering bandwidth of the second filtering circuit to a loop bandwidth of the phase-locked loop is not greater than 0.01.

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